1. Field of the Invention
The present invention relates to devices for separating debris particles and gas from fluids in machinery, such as lubricants in an engine; and more particularly to such devices that perform the separation by creating a fluid vortex.
2. Description of the Related Art
Modern turbine engines, such as those used in aircraft, are lubricated by oil which is supplied to moving engine components by a pump that draws the oil from a reservoir. The oil flows from those components into sumps within the engine from which scavenger pumps force the fluid back to the reservoir. In the course of flowing through the engine, the oil often picks up debris particles and becomes aerated due to a turbulent flow. Therefore, it is common practice for this mixture to pass through an apparatus that separates the particles and entrained gas from the lubricating oil prior to entering the reservoir.
U.S. Pat. No. 6,348,087 discloses a three-phase cyclonic separator that has upper and lower chambers with a debris collector located there between. The fluid mixture from the engine flows tangentially into the top region of the upper chamber and travels in a vortex downward past the debris separator and into the lower chamber. The cyclonic motion drives the heavier debris particles outward and downward against the walls of the upper chamber and into the debris collector. An outlet chamber beneath the lower chamber has a gas support platform which causes a gas column to form in the center region of the lower chamber with the liquid lubricant, or oil, flowing around that gas column. A gas outlet is provided at the top center of the upper chamber through which gas that has been separated from the lubricant mixture exits the separator. The liquid lubricant exits the outlet chamber from one side. The gas support platform maintains a stable interface for the gas column to form and creates a liquid barrier that directs the separated gases through the gas outlet and minimizes gas migration through the liquid outlet.
In order to maintain the gas column within the separator, a pressure balance must exist between the fluid outlet and the gas outlet which typically is achieved by a properly sized restriction at the gas outlet. Thus, a net gauge pressure is created within the separator that is necessarily higher than the pressure within the reservoir into which the liquid lubricant flows from the separator. It has been found that the pressure balance can be optimized only for a particular flow condition due to the fixed geometry of the separator. As a consequence, prior cyclonic separators did not optimally accommodate changes in the gas/oil mixture which inevitably resulted from varying engine operating conditions. The pressure balance between the liquid outlet and the gas outlet to achieve gas/oil separation efficiency for a particular set of flow conditions has been referred to as “tuning”.
Therefore, it is desirable to provide a three-phase cyclonic lubricant separator that efficiently operates over a range of flow conditions that occur during normal engine operation. Thus, it is desirable to create such a separator which is not tuned for a specific pressure balance or flow condition.